A variety of surgical techniques and devices have been proposed to assist an individual who has undergone a laryngectomy in producing relatively normal-sounding speech. For example, electronic devices which produce a generally monotonal output modulated by the vibrations received from a transducer held to the throat have been developed. This speech is rather mechanical sounding and does not approach the normal quality of human speech.
The more effective techniques for producing natural-sounding speech use the esophagus as a substitute for the larynx which has been removed. The walls of the esophagus are caused to vibrate by air which is introduced into the esophagus and then passes through the remainder of the speech tract and out through the mouth.
It is possible for some individuals to master an esophageal speech technique in which quantities of air are periodically swallowed and then released to vibrate the esophagus. This technique is difficult to master and produces speech which of necessity is limited to one or two words for each quantity of air swallowed.
Various laryngeal protheses have been proposed since the latter part of the nineteenth century. Dr. David Foulis in Scientific American, Supplement No. 115, Mar. 16, 1878, pp. 1834 to 1835 reported on a device used to bypass air from the trachea to the esophagus containing a reed which vibrated due to air flow. The speech produced by the use of such a device, however, had the monotonal qualities of the vibrating reed.
U.S. Pat. Nos. 4,060,402 and 4,060,856 to Nigel disclose a laryngeal prothesis of a generally symmetrical form comprising a hollowed main body with external tubes to fit into the trachea and a surgically-formed fistula intended to serve as a pseudo-glottis. A short fistular tube is configured with a free end formed of a thin-walled, normally collapsed tubular one-way valve (See column 3, lines 7-15) which is designed to prevent undesired reflux of saliva into the trachea but opens in response to air pressure produced by expiration, thus passing diverted air to the pharynx for phonation. This device is rather complex and the surgically-created openings and cavities required to use the device are subject to breakdown with the passage of time. In addition, the surgical techniques necessary may be contraindicated for many patients.
A much simpler device, the voice-button prosthesis developed by Dr. William R. Panje may be inserted in a surgically created tracheal-esophageal fistula. This device comprises a short tube having two closely-spaced flanges which serve to hold the device in place so that one end of the tube and one flange associated with this end are disposed within the esophagus and the other end of the tube and one flange which is associated with that end are disposed within the trachea. The esophageal end contains a one-way slit valve which permits air to travel from the trachea to the esophagus when the tracheal opening or stoma is sealed and the patient exhales.
Despite the presence of the flanges this type of device is ocassionally subject to ejection during violent movement of the anatomical structures due to, for example, coughing. In addition a substantial amount of air pressure is generally required to produce a sufficiently high volume of air flow to produce high quality speech.